2. Prior Art
Lubricating oil supplied to each of the parts within a vehicle engine is stored in an oil pan provided at a lower part of an engine. The stored lubricating oil is sucked up by an oil pump, purified through filtering by an oil filter, and the supplied to the engine again. A plate referred to as a baffle plate is provided between the oil pan and the crankshaft. The baffle plate is provided to prevent the stored lubricating oil from building up so as to tend towards one side. Normally, oil drip holes for discharging lubricating oil dropping from above to the oil pan are formed at this baffle plate.
Here, some of the lubricating oil that is provided again is utilized by hydraulic equipment provided within the engine such as, for example, a rush adjuster. When bubbles (air) are mixed within lubricating oil utilized by hydraulic equipment, there may be cases where abnormalities occur in the behavior of the hydraulic equipment. Namely, when bubbles become mixed with lubricating oil stored in the oil pan, abnormal behavior may be exhibited by the hydraulic equipment. Because of this, it is desirable for there to be as few bubbles (as little air) as possible (preferably none) mixed in with the lubricating oil stored in the oil pan.
One factor contributing to bubbles being generated in stored lubricating oil is when a large amount of lubricating oils remains on the baffle plate. Normally, lubricating oil on the baffle plate can be discharged to the oil pan from the oil drip holes. However, when the distance between the oil level of the lubricating oil stored in the oil pan and the baffle plate becomes too small, discharge of lubricating oil on the baffle plate is no longer performed in a normal manner. As a result, a large quantity of lubricating oil remains on the baffle plate. It is easy for bubbles to occur in this residual lubricating oil. The reason for this is that a counterweight is rotatably driven on the baffle plate and there is therefore interference between this counterweight and the residual lubricating oil. A further reason is that ruffles may occur in the residual lubricating oil due to rotational airstreams generated in accompaniment with rotation of a counterweight.
In order to prevent a large amount of lubricating oil from remaining, the oil pan is provided lower down, so as to create distance between the baffle plate and the oil level of the stored lubricating oil. However, this causes the engine to be high overall and is not preferable.
In Japanese patent specification No. 3072389, a baffle plate structure where a baffle plate is fastened to the bottom surface of a bearing cap is disclosed. By fastening a baffle plate to the bottom surface of a bearing cap, it is possible to create distance between the baffle plate and the oil level of the stored lubricating oil without lowering the position of the oil pan. This enables the occurrence of bubbles within the stored lubricating oil to be reduced.
However, with the above structure, it is necessary to provide a bearing surface use in fastening the baffle plate at the bottom surface of the bearing cap, which makes the overall width of the vehicle engine large. In recent years, there has been a desire for vehicle engines to be lightweight and compact. It is therefore not desirable to provide a new bearing surface etc. at the bottom surface of the bearing cap.